Abrasive apparatus



Feb. 4, 1969 P. J. POPE 3, 5,1 7

ABRASIVE APPARATUS Filed Oct. 21, 1965 v I I Sheet of 2 0 77a 2 Q 72 X 75 LOAD/N6 f FORCE O 7] Q I 20a ATTORNEY Feb. 4, 1969 P. .1. POPE v 3,425,167

ABRASI-VE APPARATUS Filed Oct. 21, 1965 Sheet 2' of 2 INvEN-roR Pgicr Fa- W A'r-roRNEfl United States Patent 3,425,167 ABRASIVE APPARATUS Peter James Pope, Windsor, England, assignor to Wilkinson Sword Limited, London, England, a British company Filed Oct. 21, 1965, Ser. No. 499,954 US. Cl. 51-80 Int. Cl. B24b 7/00, 9/00, 49/00 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to abrasive processes such as grinding, stropping, honing and polishing.

According to the present invention there is provided the method of effecting an abrasive process in which the force with which the abrasive member is applied to the material being processed is maintained at a substantially constant predetermined value.

The invention also provides apparatus for effecting an abrasive process, in which means are provided for applying the abrasive member to the material being processed with a substantially constant force of predetermined value.

The invention further provides apparatus for effecting an abrasive process, comprising at least one wheel having an abrasive surface, said wheel being mounted for pivotal movement and means for applying a predetermined constant force to said wheel in a direction to move said abrasive surface into contact with the material being processed.

One method of stropping razor blade strip according to the present invention, and apparatus for performing this method, will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic side view of the apparatus;

FIG. 2 is a part-perspective view of the arrangement for guiding the razor blade strip during stropping; and

FIG. 3 is a schematic view of the control system of the apparatus.

Referring to FIG. 1 this shows two stropping discs 10, 10a each mounted at one end of a respective one of double arms 11, 11a which are centrally mounted on a common pivot 12. For other processes the discs 10, 10a could equally well be grinding or honing wheels or polishing pads. The framework 13 in which the pivot 12 is mounted is itself mounted on a slide 14 whose position can be adjusted by control knob 15 in order to vary the distance between the pivot 12 and guide 16 through which the razor blade strip 17 (FIG. 2) passes during processing. This permits adjustment of the angle of the cutting facets formed on the edge of the blade strip 17,

The blade strip 17 is conveyed through the processing zone by a moving pegged band 18 which passes between two rigid guide portions 19, 19a which enclose the blade strip 17 with the exception of the edge whose facets are being processed. The blade guides 19, 19a serve to mini mize bending of the blade strip 17 and reduce contamination by dirt.

counterbalance weights 20, 20a are provided at the opposite end of each arm 11, 11a to that at which the discs 10, 1011 are mounted, in order that the arms are substantially balanced about the pivot 12.

Referring now to FIG. 3 this shows diagrammatically how the position of one pair of arms 11, 11a is controlled at the end remote from the discs 10, 10a, the other pair of arms, not shown in the drawing, being similarly controlled but with the force applied in the opposite direction. The arms are loaded onto the blade strip 17 by a force applied by a piston 21 of a pneumatic cylinder 22 which is supplied with air at a controlled pressure from a pressure reservoir 23 through a pressure regulator 24. A visual indication of the loading pressure is given on a gauge 25. Damping of the arms is provided by a hydraulic damper 26, the arm 11a being damped by a hydraulic damper 26a (FIGURE 1). In order to prevent the discs 10, 10a, bearing on the blade guides 19, 19a when there is no blade strip present, a further pneumatic cylinder 27 is provided the piston 28 of which is supplied with air from the pressure reservoir 23 under the control of a regulator 29, at a greater pressure than the loading cylinder 22. In order to provide the desired loading when blade strip is present a vacuum controlled diaphragm valve 30 is inserted in the pressure line to the cylinder 27, the presence of blade strip closing an air bleed hold 31 so that a vacuum pump 32 reduces the pressure on one side of the diaphragm valve 30 to cutoff the air supply to the cylinder 27 thereby allowing the discs 10, 10a to be loaded onto the blade strip at a pressure determined by the pneumatic cylinder 22.

It will be appreciated that alternative means for sensing the presence of blade strip could be employed, for example magnetic sensing means or a mechanical feeler. As an alternative to a hydraulic damper there could be used a pneumatic damper or an eddy-current damper.

Drive to the discs 10, 10a may conveniently be from one or more motors mounted on the base of the machine and driving a layshaft which is coaxial with the pivot 12, the discs 10, 10a being driven from the layshaft, for example through belt or chain drives.

It will be seen that by virtue of the controlled pressure applied by the cylinder 22 a controlled force is applied to the discs 10, 10a. Whilst the use of positive pressure has been described it will be understood that the force applied to piston 21 may be by means of partial vacuum. The counter-balancing of the discs 10, 10a by the weights 20, 20a insures that the controlled loading need only be such as is required to provide correct grinding of the strip the controlled loading does not have to balance the weight of the discs as well and thus greater sensitivity of control is obtainable.

I claim:

1. In apparatus for effecting an abrasive process,

means on said apparatus for supporting material to be processed,

an abrasive member having a surface movable relative to said material to effect abrasion thereof,

means on said apparatus supporting said abrasive member for movement towards and away from the material supporting means,

a pneumatic piston coupled to said abrasive member whereby the force applied to said piston determines the force at which said abrasive surface is applied to said material,

a pressure reservoir,

a pressure regulator, said pressure reservoir being connected to said piston through said pressure regulator for regulating the pressure to a substantially constant value,

a second pneumatic piston coupled to said abrasive member,

a second pressure regulator, said second piston being 3 connected to said pressure reservoir through said second pressure regulator which is set so that said second piston applies to said abrasive member an opposite and greater force than the force applied by the first mentioned pneumatic piston,

a pneumatic valve connected in the pneumatic path between said pressure reservoir and said second piston, said valve being operative between a first condition which inhibits a flow of gas from said reservoir to said second piston and a second condition which permits said flow, and

means for maintaining said valve in said first condition so long as material is supported in position for processing.

2. Apparatus according to claim 1 comprising damping means coupled to said abrasive member for damping oscillations thereof.

3. Apparatus according to claim 1, wherein said material is razor blade strip.

4. Apparatus according to claim 1, in which said means for maintaining said valve in said first condition comprises an enclosure having an opening to atmosphere which is substantially closed so long as material is supported in position for processing and which is opened in the absence of said material, and

source means connected to apply suction to said enclosure, the pneumatic valve being connected to be controlled by the pressure in said enclosure whereby to be maintained in said first condition so long as a partial vacuum exists in the enclosure and being set into said second condition when the pressure rises in said enclosure in the absence of said material.

5. Apparatus for effecting an abrasive process, comprising a base,

first supporting means for supporting material to be processed on said base,

an abrasive member having a surface movable relative to said material to effect abrasion thereof,

second supporting means mounting said abrasive member on said base for movement towards and away from said first supporting means,

first force-producing means coupled to said second supporting means and operative to apply said abrasive member against the material with a predetermined force,

means connected to said first supporting means and defining an enclosure having an opening to atmosphere which is substantially closed when material to be processed is present on said first supporting means and which is opened when said material is absent,

a vacuum source connected to said enclosure to apply suction thereto whereby a partial vacuum exists in said enclosure when material to be processed is present on said first supporting means and whereby the pressure in the enclosure rises in the absence of said material,

second force-producing means connected to said second supporting means and operative when actuatedto apply a counter-force to said abrasive member o'pposite to and greater in value than the first-mentioned force, and

pressure sensing means connected to respond to the pressure in said enclosure and operative to actuate the second force-producing means when the pressure in the enclosure rises in the absence of said material.

6. Apparatus according to claim 5, in which the first and second force-producing means respectively comprise first and second pneumatically operable piston-cylinder assemblies, the apparatus including a pressure source connected to said piston-cylinder assemblies and the said sensing device comprising diaphragm valve means in the supply circuit to the second piston-cylinder assembly, said diaphragm valve means being connected to respond to the pressure in said enclosure.

References Cited UNITED STATES PATENTS 1,800,307 4/1931 Marschke et al 51-99 1,902,010 3/ 1933 Anderson 5180.1 2,096,890 10/ 1937 Ferrel 5199 2,243,405 5/ 1941 Wine 51--165.03 2,648,174 8/ 1953 Bikles 5180 2,982,056 5/1961 Edqvist 51-16503 3,089,287 5/1963 Dilks 51-35 FOREIGN PATENTS 1,034,461 7/ 1953 France.

ANDREW R. JUHASZ, Primary Examiner.

G. WEIDENFELD, Assistant Examiner.

US. Cl. X.R. 51165 

